Method of assembling tool joints



Jan 23 1951i R. w. BROWN 2,539,656

METHOD OF ASSEMBLING TOOL JOINTS Filed Sept. 2, 1944 fag/M50 14/ fl/PanwPatented Jan. 23, 1951 2,539,056 I METHOD or ASSEMBLING 'roor. JOINTSRobinson W. Brown, Oklahoma City, Okla assignor to Chicago Pneumaticlfool Company, New York, N. Y., a corporation of New Jersey ApplicationSeptember 2, 1944, Serial No. 552,478

high temperatures.

An object of the invention is to assemble a tool joint with a drill pipein such effective and novel manner as to result in a strong connectionfree from weak spots or any undue local strains which might causefailure of the pipe during service. This is accomplished in the presentinvention because the compressive stresses, caused by bucking on of thejoints, are carried over the last thread and distributed onto the heavyupset portion of the pipe. Bending stresses at the last engaged threadare also minimized.

A further object is to have a tool joint which is simple and economicalto make and to assemble with a drill pipe of standard construction.

Still another object is to prevent further makeup of the threads duringservice.

According to a feature of this invention, the end of the tool joint isheated to permit the insertion of a ring therein, the ring being adaptedupon cooling of the joint to grip the drill pipe in such a manner as torelieve the latter of local stresses which are liable to cause failureof the pipe in service. According to another feature of thi invention,the heat is not applied until after the pipe and tool joint have beencompletely made up or threaded together under controlled torque, therebyobviating difficulties involved in prior methods due to the change inpitch of the threads when heated.

Other objects and features of the invention will be set forth more fullyas the specification proceeds, due reference being had to theaccompanying drawing in which:

Fig. 1 is an elevation of a tool joint completely assembled with a drillpipe according to the in vention, the drill pipe being shown infragmentary section and a portion of the joint being broken away todisclose details and relations of parts;

Fig. 2 is a side elevation of a sealing and locking ring pertaining tothe tool joint, the ring being shown undergoing heating;

Fig. 3 illustrates a step of assembling the tool joint (indicated inbroken lines) with the drill pipe, the sealing ring occupying a generalinitial position; and 4 Fig. 4 shows the tool joint, drill pipe andsealing and locking ring in fragmentary section with the tool joint andring undergoing heating preliminary to shifting the ring into finallockin and sealing position.

1 Claim. (Cl. 29-1481) When joining drill 'pipe such as used in drillingoil wells and the like, it has been found by experience that certainweaknesses are apparently inherent in the very structure of conventionaltool joints and drill pipes, as the latter frequently tend to failduring service at the last engaged thread on the pipe. In order toremedy this defect and also to insure a fiuid tight tool joint, thelatter has sometimes been welded with satisfactory results after theparts have first been screwed together cautiously in order to have nomore than the proper make-up, but such welding i tedious and costly andnecessitates considerable machine work as well as torch work when suchwelded joints are worn out and require replacement. 1

In view or these disadvantages and particularly with the foregoingobjects in view, the invention is designed to provide a tool jointadapted to be assembled with a drill pipe with the aid of a sealing andlocking ring, by bringing the parts together in expeditious andefiective manner without resorting to welding or use of very hightemperatures.

Hence, referring again to the drawing, the drill pipe II has a standardpipe thread I I on the end thereof and is formed internally with theconventional upset portion l2. The tool joint I3 has a standard internalpipe thread l4 corresponding to the thread It on the drill pipe, butbetween the internal thread It and the end of the joint is a relativelylong counterbore l5 concentric with the thread, the inner end of thecounterbore being relieved by a chamfer or taper l6 merging with thethread l4. At the end the joint optionally terminaes in a bevelledshoulder I1 which is useful when raising the drill pipe and joint in awell casing, as the bevel prevents the upper end of the joint fromcatching upon any obstruction which might interfere with the raising ofsaid drill pipe. Exteriorly along the major portion of the length of thetool joint, the latter has a substantially uniform diameter frombevelled shoulder I! to the shoulder 18 surmounted by a tapered threadportion IS. The external threads I9 are characteristic of a tool jointpin element and form a quick detachable connection with the internalthreads on a tool joint box element, which in turn may be secured toanother section of drill pipe in the same manner that pin element 13 issecured to pipe 10.

Within the tool joint, the inner end of internal thread I4 terminatesbut a short disance from a tapered portion 23 which connects thethreaded 3 section s! 292; 24 of reduced diameter which continues upthrough threaded portion I9. To complete the assembly, a relatively thinbut wide ring 25 is included, the inside diameter making the ring aclose fit on the exterior of pipe it, while the external diameter isnormall several thousandths of an inch greater than the internaldiameter of counterbore IS in the tool joint, which circumstance servesan important purpose set forth hereafter.

In assembling the drill pipe and tool joint,

ring 25 is first passed over thread II and slipped along pipe Hi to ageneral initial position on a smooth cylindrical portion 26 of the pipe,and then the tool joint is screwed in upon the latter as indicated bythe arrows in Fig. 3, this operation being performed by a bucking-onmachine under controlled torque, that is, in such manner as to insurethat the tool joint is screwed on the pipe only to a predetermineddegree or make-up in order to avoid setting up undesirable strains ineither the joint or the pipe which might produce a weak spot ultimatelyleading to failure of the pipe in service.

Thereafter, the joint and pipe assemblage is removed to a lathe or othermachine and rotated about the longitudinal axis of the pipe and one ormore heating jets 21 (one shown) directed at shoulder l1 and generallyon the end of the tool joint exteriorly of the counterbore IS in orderto expand the latter to a considerable extent. At this juncture, ring 25is slid along the drill pipe and introduced all the way into thecounterbore and the finished assemblag allowed to cool. As the shoulderI1 and the hollow end of the tool joint containing the counterborecontracts, it tightly grips the ring and is fixed thereon in a rigidgrip which includes the hold of the ring on the pipe and very largelyrelieves the threads II and ll of the bending and torsional strains. Inthe resulting joint rigidity is obtained with the parts held together bya shrink fit which also insures fluid tightness of said joint.

To accommodate the ring 25, the portion 26 of the pipe i0 adjoining thethreads II should be turned smooth and concentric with the pipe thread.This is the only special feature of construction of the pipe l0 which inall other respects may be a standard A. P. I. internal upset drill pipe.If desired, portion 26 could be upset slightly above the outsidediameter of the pipe body. Furthermore, the invention is also applicableto external upset, internal flush, drill pipe.

While ring 25 has been described as capable of being slipped along thedrill pipe, the ring in its final state is tightly clamped to the pipeit due to the compressive force of the adjacent end of the tool joint l3upon shrinkage of the latter. According to a modification of thisinvention, the gripping action of the ring 25 is increased by making thebore of the ring, in its normal condition, slightly less than theoutside diameter of pipe Hi. In the modified process, the first step isto heat the ring by a group of heating jets 21 (one shown in Fig. 2).The'heated ring is then slipped on the pipe to the preliminary orinitial general position of Figs. 3 and 4. The remaining steps of theprocess are the same as those previously described and occur while thering'remains warm and before it has an opportunity to shrink to itsnormal diameter. Upon final cooling of the parts the ring 25 is under astrain resulting from its own expansion and partial contraction, inaddition to the compressive force from the surrounding tool joint.

For the purpose of heating the tool joint and also the ring, gas or oilfed flames or jets 21 have been shown, but in either or both cases, sucharrangements are readily replaced by a heating ring, heating by anysuitable means such as gas, oil, electricity, etc., and the temperaturemaintained uniform about the joint or ring as the case may be. The tooljoint, drill pipe and ring are preferably made of conventional steelalloy suitable for said parts, and when assembled as described above,need not be welded or assembled with the aid of very high temperatures,but are therefore expeditiously assembled in such manner as to avoidstrain on any particular thread of the pipe. When replacing joints, itis necessary only to cut off the old Joints with a torch, clean thethreads, replace the rings and install new joints.

What is claimed is:

A method of assembling a hollow tool Joint having a counterbore in oneend and an internal pipe thread within the inner end of saidcounterbore, with a drill pipe having a substantially uniform externaldiameter and an external pipe thread on the end thereof, and with asealing and locking ring, the diameter of the counterbore being uniformand slightly less than the external diameter of the sealing and lockingring and the internal diameter of said ring being uniform and slightlyless than said uniform diameter of the drill pipe which method consistsin heating the ring to expand it and passing the heated ring in upon thedrill pipe to a general initial position within the inner end of thethread on said pipe, screwing the pipe into the tool joint with theexternal thread of said pipe engaging with the internal thread of saidtool joint up to a predetermined degree of torque, heating thecounterbored portion of the tool joint in order to expand saidcounterbored portion, shifting the ring from its initial position intothe counterbore, and al-- lowing the assembled tool joint and drill pipeto cool and shrink fit said counterbored portion of the tool joint uponthe sealing and locking ring and clamp the latter upon said drill pipe.

ROBINSON W. BROWN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

